docs: def add_task(self, command, name=None, **kwargs):
          """ Adds a new Task to the graph with no edges. """
  
          logger.debug('Adding task with command {0} to job {1}'.format(command, self.name))
          if not self.state.allow_change_graph:
              raise DagobahError("job's graph is immutable in its current state: %s"
                                 % self.state.status)
  
          if name is None:
              name = command
          new_task = Task(self, command, name, **kwargs)
          self.tasks[name] = new_task
          self.add_node(name)
          self.commit()